On Sun, Mar 27, 2022 at 8:05 PM Marc MERLIN <marc@xxxxxxxxxxx> wrote: > > OMG, using a USB adapter eats 4 setors? I had no idea... > Sure enough, I did connect the drives via USB for diagnosis since I had > run out of sata ports. None of my SATA-USB enclosures behave this way. But what it does do is mask (lie) the true physical sector size, claiming it's 512 bytes instead of 4096 bytes. I've also seen enclosures turn a 512 byte logical sector drive into a 4096 byte logical sector drive, which is a real PITA because it completely messes up the GPT. My understanding of the logic of GPT format is atomic modifications that are crash safe (that's up to the tool to do correctly too but the spec has a pretty specific order each sector is supposed to be written), but in practice this is another PITA for a significant minority of users who end up putting an internal drive into an enclosure and bam - can't read the drive at all. It'd be kinda neat if this condition could be detected and have a device mapper target setup to deal with it. -- Chris Murphy
